“…Both BaCaCuO and TlBaCaCuO precursor films have been used, and a variety of methods have been used in their preparation, including sputtering, 19-28 laser ablation, 29,30 evaporation, [31][32][33] and spray pyrolysis. 23,36 Other thallination techniques have also been attempted. 19,20,29,31,[33][34][35] A few studies have used a thallium oxide source held at a lower temperature than that of the film to maintain a thallous oxide overpressure.…”